A small survey to check members success in swapping out the air cleaners would help trying to settle on my problem: I have kept the original housing on my non-ram air Cleveland because it keeps it original and also the engine dyno-ed better with the OEM housing in place than with no filter at all. Problem is that the large housing 1. requires a low rise manifold to clear the plain hood and 2. had to have relief cut in the front to clear the MSD dizzy. Here is the question; has anyone swapped out to a plain 14" round and connected both the passenger side valve cover vent as well as the carbon canister paper hose for fumes? If so, did you see a difference in performance and what mfg/model did you use and how did you hook up the paper hose? I'm torn between the original look and going with an aftermarket that might allow me to use mid-rise manifold and also look a little cooler. thanks for any input!

Why not a Ford housing from a different car/engine combo? There may be one or some with bases dropped (down over the carb) more than the Mustang unit. There are different filter and overall diameters available, too.
I've even modified housings to include a second matching snorkel, and ones with shortened snorkels to add flex hose ductwork to. Looked OE with the proper paint and lid decal, but wasn't.

I have several spares, but haven't looked at them for years. Kept them for the same reason of mixing and matching to get the proper look and function. Unfortunately even if I looked at them, I couldn't tell you which ones came from what vehicle originally.

There is a "cosmetic" air cleaner on my engine now
as seen below. It only has one connection which I use for
the breather hose. Would like to also attach the charcoal
cannister, but no where to put it. Don't like having parts
in the engine bay that serve no purpose, like the horn. BUT,
it is original equipment and should function. So I may go back
to original cleaner which I still have. One problem is the original
carb was probably a 600 CFM while now there is a 770. Will the
factory installed cleaner be able to supply enough air through the
snorkel? The original cleaner is fully functional with all switches
and valves intact. Even bought a new K&N filter to fit. When you
look at the carb's throttle body it is twice the size of the snorkel.